Thanks for noticing -- it is, in fact, I. And I mentioned this "forthcoming" book on Aug. 30 (I think), in a response to my own thread about the CW Sesquicentenary events. Of which next summer's AEBG IV may be one.
The book is actually in print, as of about two weeks ago -- and in case anybody wants it, there's a way to get it cheaper than the cover price. It isn't a book of music, but a commentary on the sources of the texts (my part) and tunes (Warren's part -- and most of the book, really) in The Sacred Harp -- specifically, the 1991 edition, of what has been known as the Denson Revision. But basically, it's an 1844 collection -- and most of the sources are that old, or older. A number of more modern tunes have crept in, but usually as new settings for the earlier sort of texts (by Watts, Wesley, and other well known Brits -- and a couple hundred more obscure figures, many of them American camp-meeting revivalists from the southern and western states).